Steel reinforced Concrete retaining wall supporting an under-pinning operation in Moraira.

Video version or scroll down for photos

The footings are dug and the back wall is lined first with Geo-Textile material to allow just the water through to the waterproof steel reinforced wall, and no silt. This passes down the inside of the structure into the porous pipe "French Drain" located at the base. Steel mesh cages are built on-site and by hand because there is limited space and access for the heavy gage steel.

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You can see that the structure will have a cantilever foot and anti-roll peg at its base to ensure that the structure is unable to rotate from the current incline. Once in place the micro piles will be drilled through the end of the foot to further ensure no rotation.

The plastic membrane is to ensure that none of the concrete passes into the Geo-Textile material or into the crevices of the original stone wall. This is to ensure that there remains a clear path for the water to drain from the wall, through the Geo-tex into the French drain at the base and then away. The extra plastic above and to the sides is to protect the walls and patios of the house.

Special spacers are added to make sure that there is sufficient gap between the steel and the wall for the concrete to pass behind. The shuttering along the top is to stop any concrete splash over.

The concrete is then loose pumped into the foundation and vibrated to remove the air

From this angle you can see that the concrete gets pumped right into the base of the foundation ensuring that the whole wall and foot section are poured as one solid unit.

Now we add pressure to the hose which forces the concrete into the cage structure. This compacts to form a very strong concrete wall. The quantity of cement in the mixture is very high producing a very hard concrete.

The high quantity and the presure make the concrete very sticky, perfect for building up the layers around the steel.

The layers build up until the steel mesh starts to disappear. This wall for example is 50cm thick at the base tapering to 40cm at the top. A very solid structure!

The concrete is then leveled off so that the depth is constant along the whole area. In this case the surface is made rough finish as we are going to add stone pieces to finish the wall. The rough surface together with a special chemical will help bond the stone pieces to the concrete surface.

Here we have begun cladding the retaining wall with heavy grade stone pieces. Although the surface of the concrete was left rough we first pain the wall with a bonding agent to ensure that the pieces stick properly.

The layers are built up, first fixed on and then pointed or grouted with a mortar.

The original retaining wall was a dry stone wall, typical of the Moraira / Costa Blanca area. We matched the stone colour as closely as possible so that when all is finished it will be difficult to notice that the retaining wall was retrofitted.

The corner proved to be very dificult to set right, but the outcome was fantastic.

Here you can see that even though the stone is rough cast the levels of the wall have remained true.

As you can see, corner going in well and the stone is creeping to the top.

Once the stone cladding is finished we reconnect new down pipes for the terrace drainage.

All the cracks in the old block walls are opened and treated with a flexible cement, and then repainted.

You would never know that we had built a 40 ton steel reinforced cantilever wall, it all looks original.


All painted and finished. Many thanks to the clients, David and Jeannine in Moraira, a pleasure working with you!


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